blob: 80c25f098c89919f0072e797b44fa47bd0c66464 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/*
* realpath.c -- canonicalize pathname by removing symlinks
* Copyright (C) 1993 Rick Sladkey <jrs@world.std.com>
* Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <limits.h> /* for PATH_MAX */
#include <sys/param.h> /* for MAXPATHLEN */
#include <errno.h>
#include <stdlib.h>
#include <sys/stat.h> /* for S_IFLNK */
#ifndef PATH_MAX
#ifdef _POSIX_VERSION
#define PATH_MAX _POSIX_PATH_MAX
#else
#ifdef MAXPATHLEN
#define PATH_MAX MAXPATHLEN
#else
#define PATH_MAX 1024
#endif
#endif
#endif
#define MAX_READLINKS 32
char *realpath(const char *path, char got_path[])
{
char copy_path[PATH_MAX];
char *max_path, *new_path, *allocated_path;
size_t path_len;
int readlinks = 0;
#ifdef S_IFLNK
int link_len;
#endif
if (path == NULL) {
__set_errno(EINVAL);
return NULL;
}
if (*path == '\0') {
__set_errno(ENOENT);
return NULL;
}
/* Make a copy of the source path since we may need to modify it. */
path_len = strlen(path);
if (path_len >= PATH_MAX - 2) {
__set_errno(ENAMETOOLONG);
return NULL;
}
/* Copy so that path is at the end of copy_path[] */
strcpy(copy_path + (PATH_MAX-1) - path_len, path);
path = copy_path + (PATH_MAX-1) - path_len;
allocated_path = got_path ? NULL : (got_path = malloc(PATH_MAX));
max_path = got_path + PATH_MAX - 2; /* points to last non-NUL char */
new_path = got_path;
if (*path != '/') {
/* If it's a relative pathname use getcwd for starters. */
if (!getcwd(new_path, PATH_MAX - 1))
goto err;
new_path += strlen(new_path);
if (new_path[-1] != '/')
*new_path++ = '/';
} else {
*new_path++ = '/';
path++;
}
/* Expand each slash-separated pathname component. */
while (*path != '\0') {
/* Ignore stray "/". */
if (*path == '/') {
path++;
continue;
}
if (*path == '.') {
/* Ignore ".". */
if (path[1] == '\0' || path[1] == '/') {
path++;
continue;
}
if (path[1] == '.') {
if (path[2] == '\0' || path[2] == '/') {
path += 2;
/* Ignore ".." at root. */
if (new_path == got_path + 1)
continue;
/* Handle ".." by backing up. */
while ((--new_path)[-1] != '/');
continue;
}
}
}
/* Safely copy the next pathname component. */
while (*path != '\0' && *path != '/') {
if (new_path > max_path) {
__set_errno(ENAMETOOLONG);
err:
free(allocated_path);
return NULL;
}
*new_path++ = *path++;
}
#ifdef S_IFLNK
/* Protect against infinite loops. */
if (readlinks++ > MAX_READLINKS) {
__set_errno(ELOOP);
goto err;
}
path_len = strlen(path);
/* See if last (so far) pathname component is a symlink. */
*new_path = '\0';
{
int sv_errno = errno;
link_len = readlink(got_path, copy_path, PATH_MAX - 1);
if (link_len < 0) {
/* EINVAL means the file exists but isn't a symlink. */
if (errno != EINVAL) {
goto err;
}
} else {
/* Safe sex check. */
if (path_len + link_len >= PATH_MAX - 2) {
__set_errno(ENAMETOOLONG);
goto err;
}
/* Note: readlink doesn't add the null byte. */
/* copy_path[link_len] = '\0'; - we don't need it too */
if (*copy_path == '/')
/* Start over for an absolute symlink. */
new_path = got_path;
else
/* Otherwise back up over this component. */
while (*(--new_path) != '/');
/* Prepend symlink contents to path. */
memmove(copy_path + (PATH_MAX-1) - link_len - path_len, copy_path, link_len);
path = copy_path + (PATH_MAX-1) - link_len - path_len;
}
__set_errno(sv_errno);
}
#endif /* S_IFLNK */
*new_path++ = '/';
}
/* Delete trailing slash but don't whomp a lone slash. */
if (new_path != got_path + 1 && new_path[-1] == '/')
new_path--;
/* Make sure it's null terminated. */
*new_path = '\0';
return got_path;
}
|
